The invention relates to gas meters. More particularly, the invention relates to gas meter changeout.
A well-developed field exists in meters for residential and commercial natural gas service. An exemplary meter has an inlet port/fitting receiving gas flow from a supply line and an outlet port/fitting delivering the gas to a building line. Although the inlet fitting and outlet fitting may be directly connected to respective fittings of the supply line and building line, common installations use a cast metallic meter bar. The meter bar has a first pair or fittings for respectively mating with fittings of the supply line and building line and then a second pair of fittings for respectively mating with the meter fittings (directly or indirectly). The second pair may have an on-center spacing the same as a standard on-center spacing of the fittings of the associated class of meter.
Meters often have to be replaced. When replacing a meter, it is undesirable to terminate all gas flow to the building line. Even if a full flow is not maintained during changeout (changeover), it may be desired to maintain a sufficient flow to keep pilots lit. Some changeover systems involve connection to a temporary gas supply such as a portable gas supply. Others involve bypassing the meter. Some bypass systems involve the in situ assembly of a temporary bypass conduit which is subsequently removed. Others are preassembled and remain in place after changeout. An example of these involves bypass meter bars.
A.Y. McDonald Mfg. Co., Dubuque, Iowa, manufactures several bypass meter bar systems. An exemplary such system has a cast body formed essentially as a combination of a pair of elbows and a bypass conduit joining the elbows. One elbow has an inlet from the supply line and an outlet to the meter inlet. The other elbow has an inlet from the meter outlet and an outlet to the building line. The bypass conduit extends between the elbows. Each elbow carries a three-way valve. An inlet valve has a first condition establishing communication between the supply line and meter while blocking the bypass conduit. An outlet valve likewise has a first condition establishing communication between the meter and the building line while blocking the bypass. Thus, the two first conditions allow normal operation of the meter.
In its second condition, the inlet valve establishes communication between the supply line and the bypass conduit while blocking the meter inlet. In its second condition, the outlet valve establishes communication between the bypass conduit and the building line while blocking the meter outlet. Having both valves in their second conditions is a bypass condition allowing the meter to be removed and replaced. In variations, one or both valves may have additional conditions. To avoid gas theft, the valves may be lockable in their respective first conditions.